On a spring Sunday in a Soho penthouse, ten people have gathered for a digital mapping "Edit-A-Thon." Potted plants grow to the ceiling and soft cork carpets the floor. At a long wooden table, an energetic woman named Liz Barry is showing me how to map my neighborhood. "This is what you'll see when you look at OpenStreetMap," she says.

High Road is a framework for normalizing the rendering of highways from OSM data, a critical piece of every OSM-based road map we’ve ever designed at Stamen. Deciding exactly which kinds of roads appear at each zoom level can really be done just once, and ideally shouldn’t be part of a lengthy database query in your stylesheet. In Cascadenik and regular Mapnik’s XML-based layer definitions, long queries balloon the size of a style until it’s impossible to scan quickly. In Carto’s JSON-based layer definitions the multiline-formatting of a complex query is completely out of the question. Further, each system has its own preferred way of helping you handle road casings.

We’re proud to give you a sneak peak of Carto, one of the components of TileMill, our upcoming full-featured map design studio that lets you rapidly design completely custom maps. Carto is a CSS-like map styling language based on less.js. This gets us all the syntactic goodies such as nested styles and named variables.

Web Maps Studio is a suite of tools that gives web developers everything they need to create customized, interactive map based web apps. Full integration with Style Editor, Data Market place and CloudMade’s other geo services means that developing feature-rich web app has never been easier.

TileMill is an application for making beautiful maps. Whether you're a journalist, web designer, researcher, or seasoned cartographer, TileMill is the design studio you need to create compelling, interactive maps.

Mapstraction is a programming library that provides a common interface for numerous javascript mapping libraries to enable switching from one to another as smoothly as possible. Developers can code their web applications once, and then easily switch the mapping provider based on project needs, terms and conditions, and new functionality.

Users can switch maps as desired based on personal taste and quality of maps in their local area. Various tools built on top of Mapstraction allow users to easily integrate maps into their own sites, and configure them with different controls, styles, and provider.

OpenLayers makes it easy to put a dynamic map in any web page. It can display map tiles and markers loaded from any source. OpenLayers has been developed to further the use of geographic information of all kinds. OpenLayers is completely free, Open Source JavaScript, released under the 2-clause BSD License (also known as the FreeBSD).

Leaflet is a modern, lightweight open-source JavaScript library for mobile-friendly interactive maps. It is developed by Vladimir Agafonkin of CloudMade with a team of dedicated contributors. Weighing just about 22 KB of gzipped JS code, it still has all the features most developers ever need for online maps, while providing a fast, pleasant user experience.

It is built from the ground up to work efficiently and smoothly on both desktop and mobile platforms like iOS and Android, taking advantage of HTML5 and CSS3 on modern browsers. The focus is on usability, performance, small size, A-grade browser support and an easy-to-use API with convention over configuration. The OOP-based code of the library is designed to be modular, extensible and very easy to understand.

Modest Maps is a small, extensible, and free library for designers and developers who want to use interactive maps in their own projects. It provides a core set of features in a tight, clean package with plenty of hooks for additional functionality.

We at StreetEasy decided to build our own maps using, among other tools, OpenStreetMap, TileMill, MapBox and Leaflet, instead of paying hundreds of thousands of dollars per year to Google. And yes, the money pushed us into doing it, but we're happier with the result because we now control the contents of our maps. (and now there is a follow up post too https://plus.google.com/118383351194421484817/posts/8x6xSQYypwt )